The performance, reliability and lifetime of electronic circuits are affected by the temperature of the various circuit components. Power electronics, in particular, usually have one or more components that generate large amounts of heat, and thus may require heat transfer augmentation structures to dissipate this heat and thereby maintain acceptable operating temperatures. Constraints on the maximum size of a circuit can further increase the difficulty of removing heat, making thermal management an important aspect of power electronics design.
A particularly difficult problem is the removal of heat from printed circuit board (PCB) mounted inductors and transformers. The operation of the circuit results in the generation of large amounts of heat within the core and a resulting increase in core temperature. Due to the desirability of having the inductor occupy a small surface area of the PCB, and the normal inductor geometry of having a core surrounded by a winding, it can be difficult to transfer heat from the core to the surrounding environment.
More specifically, prior art transformers, and in particular surface-mounted transformers for power electronics, typically include windings around torroidal cores. The core in such a transformer is surrounded by the winding wires, which wrap around a significant portion, if not the entire outer surface of the torroid. Heat within the core can therefore only be removed by conduction through the wires of the winding to an adjacent heat sink. The torroidal core also wastes space because it includes a large unoccupied hole in its center.
What is needed is an improved surface-mountable design that provides for improved space utilization as well as enhanced heat transfer from the core of a transformer or inductor to a heat sink. Such an inductor or transformer should have a small footprint, be efficient, inexpensive, and compatible with conventional surface mount technology, such as enabling reflow soldering of the inductor or transformer to a PCB.